1. Field of the Invention
The present invention relates generally to electronic mixers and more specifically to doublebalanced electronic mixers fabricated using printed circuit and thin film technology.
2. Description of the Prior Art
A detailed description of state-of-the-art mixers is given in "RF Signal Processing Component", Watkins-Johnson Company, 1978, pp. 374-394, and such description is incorporated herein by reference. As pointed out in such reference, the manufacture of double-balanced mixers using thin film technology is well known. However, heretofore, in order to obtain the IF output signal without disrupting the balance between the LO input signal circuit and the RF input signal circuit, it was necessary to use fine wires, ferrite beads or other mechanical techniques. Such practices are far less than ideal and often require delicate "hand tweeking" by a highly skilled technician in order to make the device operational.
Another disadvantage of prior art devices is that they are fabricated using at least two printed circuit "cards." This, of course, means that the cost of the device is higher than would be the case for a single card embodiment.